Mounting arrangement for a bearing of axial flow turbomachinery having variable pitch stationary blades

ABSTRACT

Axial flow turbomachinery having at least one stage of variable pitch stationary blades has an annular outer casing and a main frame supporting a main shaft bearing. Each blade of a selected stage includes a blade trunnion coaxial with the blade and a passage extends through the blade and blade trunnion. The outer casing includes a hollow support cylinder in which the blade trunnion is disposed. A rod which is disposed in the passage is secured at its outer end to the casing and at its inner end to the main frame. The pitch of the blade is varied by an eccentric crank which extends through a slot in the support cylinder and is secured to the blade trunnion, the blade being freely rotatable independently of the rod.

United States Patent Ciokajlo [4 Nov. 26, 1974 MOUNTING ARRANGEMENT FOR A 3,312,448 4/1967 111111, Jr. et al 415/175 BEARING 0F AXIAL FLOW 3,582,231 6/1971 Zerlauth 415/175 TURBOMACHINERY HAVING VARIABLE PITCH STATIONARY BLADES [75] Inventor: John J. Ciokajlo, Loveland, Ohio [73] Assignee: General Electric Company,

Cincinnati, Ohio [22] Filed: Nov. 2, 1973 [21] Appl. No.: 412,321

[52] US. Cl 415/149, 415/175, 415/178, 308/187 [51] Int. Cl. F04d 29/46, F04d 29/56, FOld 5/00 [58] Field of Search 415/149, 147, 178, 160, 415/175, 176; 184/611; 308/187 [56] References Cited UNITED STATES PATENTS 2,414,788 1/1947 Altorfer et al. l84/6.ll 2,680,001 6/1954 Batt 184/611 2.836.393 5/1958 Payne et al. 415/178 3,084,849 4/1963 Dennison 415/175 A'I/I/J (and Primary Examiner-Henry F. Raduazo Attorney, Agent, or FirmLawrence, Derek R; Lee H. Sachs [57] ABSTRACT Axial flow turbomachinery having at least one stage of variable pitch stationary blades has an annular outer casing and a main frame supporting a main shaft bearing. Each blade of a selected stage includes a blade trunnion coaxial with the blade and a passage extends through the blade and blade trunnion. The outer casing includes a hollow support cylinder in which the blade trunnion is disposed. A rod which is disposed in the passage is secured at its outer end to the casing and at its inner end to the main frame. The pitch of the blade is varied by an eccentric crank which extends through a slot in the support cylinder and is secured to the blade trunnion, the blade being freely rotatable independently of the rod.

11 Claims, 6 Drawing Figures PATENT}; rznv 2 6 I974 3.850544 SHEEP 1 OF 2 1'1 III 7 /4 /Z /i j}! j! 4(2 (2 if H, I [Z 2 MOUNTING ARRANGEMENT FOR A BEARING OF AXIAL FLOW TURBOMACHINERY HAVING VARIABLE PITCH STATIONARY BLADES BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to axial flow turbomachinery and more particularly to a mounting arrangement for a main shaft bearing of such turbomachinery.

2. Description of the Prior Art It is necessary in axial flow turbomachinery, such as the compressor or turbine of an axial flow gas turbine jet engine, to provide at least one main shaft to which the rotating parts of the turbomachinery are secured and to mount the main shaft for rotation relative to the stationary parts of the turbomachinery. Such mounting is normally accomplished by providing a main shaft bearings at two or more locations along the shaft and securing the hearings to the casing of the turbomachinery.

When such turbomachinery is used in an axial flow gas turbine jet engine, a separate engine casing section having struts secured to the main shaft bearing is used. Those portions of the struts extending through the engine airflow path are streamlined in order'to reduce pressure losses and are as small as possible in cross section in order to minimize blockage of the airflow path. The usual arrangement is to have a front main shaft bearing supported by a separate engine casing section near the compressor and a rear main shaft bearing supported by another separate engine casing section near the turbine.

Since the stationary blades of such turbomachinery are supported by the casing of the turbomachinery, an arrangement may be used whereby the blades are used as a portion of the struts securing the main shaft bearing to the casing. When such turbomachinery is used for the compressor or turbine of an axial flow gas turbine jet engine, this arrangement eliminates the need for a searate engine casing section. As a consequence, the overall length of the engine is reduced, with an attendant weight reduction, and blockage of the airflow path and pressure losses caused by the separate struts are eliminated.

However, it has been proposed to provide such turbomachinery with stationary blades mounted to the casing so that their pitch can be varied, a feature which greatly increases turbomachinery performance. When variable pitch stationary blades are used, the blades must of course be freely rotatable about their respective axes, thus preventing the use of the blades as struts because such use requires that the blades fonna fixed structural link between the casing and the main shaft bearing. When turbomachinery having variable pitch stationary blades is used as the compressor or turbine of an axial flow gas turbine jet engine, a separate engine casing section must be used to secure the main shaft bearings. The increased turbomachinery performance attained from using variable pitch stationary blades is thus degraded due to the added engine length and weight, blockage of the airflow path and pressure losses, all of which are a consequence of the use of a separate engine casing section.

The present invention provides a mounting arrangement for securing a main shaft bearing of axial flow turbomachinery having variable pitch stationary blades. The mounting arrangement of the present invention eliminates the need for a separate casing section to support the main shaft bearing, thus making. the present mounting arrangement particularly useful in axial flow gas turbine jet engines using such turbomachinery.

SUMMARY OF THE INVENTION It is a general object of this invention to provide a new and improved mounting arrangement for securing a main shaft bearing of axial flow turbomachinery having at least one stage of variable pitch stationary blades.

In accordance with the present invention, the mounting arrangement comprises the annular outer casing of the axial flow turbomachinery and a main frame which supports the main shaft bearing. The main frame is secured to the outer casing by a plurality of supports, each blade of a selected stage having one of the supports associated therewith. Each support includes a rod disposed in a passage in the associated blade, the blade being freely rotatable. without interference from the rod. Each support further includes the outer casing, which has a first retaining means for preventing radially inward movement of the rod and second retaining means for preventing movement of the rod normal to its axis. The main frame includes a plurality of bosses, each support also including one of the bosses wherein the selected boss is restrained from radially inward and axial movement by the rod.

DETAILED DESCRIPTION OF THE DRAWINGS A more complete understanding of this invention may be had by reference to the specification when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic sectional view taken along the axis of an axial flow gas turbine jet engine having variable pitch compressor stator vanes.

FIG. 2 is a detailed view of one of the variable pitch stator vanes shown in FIG. I.

FIG. 3 is a sectional view taken along line IIIIII of FIG. 1. 1

FIG. 4 is a sectional view taken along line IVIV of FIG. 3 and is a detailed view of one embodiment of the present invention.

FIG. 5 is a detailed view of a second embodiment of I the present invention.

FIG. 6 is a detailed view of a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Referring now to FIGS. 1 and 2, axial flow gas turbine jet engine 10 has a diffuser 11, a three-stage axial flow compressor 12, a combustor 14, a single stage axial flow turbine 16, and an exhaust nozzle 18. The blades 20 of compressor 12 and the buckets 22 of turbine 16 are secured in any suitable manner to main shaft 24 so that blades 20, buckets 22 and main shaft 24 rotate as a unit. Shaft 24 is mounted for rotation in a front main shaft bearing 26 and a rear main shaft bearing 27.

Compressor 12 has an annular outer casing 31 and variable pitch stator vanes 32. Each stator vane 32 has a circular shoulder 33 at the vane tip and casing 31 has a circular recess 34 at the location of each stator vane 32, circular recess 34 mating with circular shoulder 33 of stator vane 32 to define an axis of rotation 35 of stator vane 32. Each stator vane 32 includes a radially extending vane trunnion 36 of circular cross-section which is coaxial with axis of rotation 35 and each vane trunnion 36 extends through a circular opening 37 in casing 31. A raised circular flange 37a surrounds each opening 37.

Vane trunnion 36 includes rotation means comprising an eccentric crank 38 which is secured to vane trunnion 36 in torque transmitting relation by spline joint 39. Spline joint 39 includes external spline teeth on vane trunnion 36 which mate with internal spline teeth on a ring 40 which is integral with eccentric crank 38. Snap ring 41 fits into a circumferential recess 41a in vane trunnion 36 and cooperates with ring 40, which bears against circular flange 37a, in order to restrain stator vane 32 from radially inward movement. Stator vane 32 is restrained from radially outward movement by circular shoulder 33 and circular recess 34.

A circumferentially extending actuating ring 42 is pivoted to each eccentric crank 38. Actuators (not shown) move actuating ring 42 in a circumferential direction, thereby moving eccentric crank 38 in an arcuate path, rotating vane trunnion 36, and changing the pitch of the stator vane 32. To further stabilize stator vane 32 for rotation about axis 35, inner flowpath 43 is provided with a circular recess 44 at the location of each stator vane 32 which recess mates with a circular shoulder 45 on each stator vane root.

Rear main shaft bearing 27 is supported by a rear main frame 46. Rear main frame 46 is a truncated cone secured at its inner end to rear main shaft bearing 27 and at its outer end to turbine nozzles 47, which turbine nozzles are in turn secured to a turbine outer casing 48. Front main shaft bearing 26 is supported by a front main frame 49. Front main frame 49 is a truncated cone secured at its inner end to front main shaft bearing 26. Front main frame 49 and rear main frame 46 have lubricant passages machined therein, or otherwise associated therewith, to convey lubricant to bearings 26 and 27, respectively.

The structure described thus far in connection with FIGS. 1 and 2 is intended only to be representative of the configuration of a conventional axial flow gas turbine jet engine having an axial flow compressor with variable pitch stator vanes. For convenience, the present invention is described making reference to the axial flow compressor described above, but-it will be clear to one skilled in the art that the invention is not limited to such and may be used with any axial flow turbomachinery having variable pitch stationary blades.

Referring now to FIGS. 3 and 4, one embodiment of the present invention is shown in detail. Each stator vane 32' of a selected stage of compressor 12, here chosen as the first stage (see FIG..1), has a support 51 associated therewith, which supports 51 secure front main frame 49 to outer casing 31. Each vane 32' has an axis of rotation defined by a circular shoulder 33 at the vane tip which shoulder mates with a circular recess 34' in casing 31. Each vane 32 is also stabilized for rotation by a circular shoulder. 45' at the stator vane root which shoulder mates with a circular recess 44' in inner flowpath 43, in a manner similar to that described above. Each vane 32 also includes a vane trunnion 36' which is coaxial with axis 35.

Each support 51 includes a hollow, radially directed support cylinder 54 within which vane trunnion 36 is disposed. A hollow rod 56 is disposed in a passage 52 which extends through vane 32 and vane trunnion 36.

Rod 56 has an inner end which is secured to a boss 58 on the outer periphery of front main frame 49. Boss 58 includes a spool 60 into which rod 56 extends, and rod 56 is brazed, or otherwise suitably secured, to spool 60. The inner end of rod 56 communicates, through an aperture 62 in the bottom of spool 60, with a lubricant passage 63. t

The outer end of rod 56 isrestrained from radially inward movement by nut 64 threaded into rod 56 which nut cooperates with a washer 66 suitably secured to the outer end of support cylinder 54. The outer end of rod 56 extends through an aperture 68 in washer 66 and aperture 68 restrains rod 56 from movement normal to the axis of rod 56.

Front main shaft bearing 26 is properly positioned by I tightening nuts 64 against washers 66 on the support cylinders 54. Rods 56 are then pretensioned by further tightening nuts 64. This arrangement secures bosses 58 in place and in turn secures front main frame 49 and front bearing 26. Front main frame 49 is shown as a truncated cone having bosses 58 on its outer periphery, but those skilled in the art will of course recognize that other structure is suitable for use as front main frame 49 without departing from the spirit of the invention.

In order to rotate vane 32', vane trunnion 36' has a spline joint 39 similar to spline joint 39 described above in connection with stator vanes 32. An arcuate slot 70 is formed in support cylinder 54 and eccentric crank 38 extends through arcuate slot 70. Support cylinder 54 includes a shoulder 72 against which a ring 40 integral with eccentric crank 38 bears and a snap ring 41 fits into a circumferential recess 41a and cooperates with ring 40 and vane trunnion 36' in order to restrain vane 32' from radially inward movement. Circular shoulder 33 and circular recess 34' restrain vane 32' from radially outward movement.

In engines experiencing large pressure differentials across front main frame 49 or having main shaft bearings experiencing large axial loading, it is advisable to prevent deflection of rod 56 to as great a degree as possible so that rod 56 will not bind within passage 52, thus preventing free rotation of vane 32 with respect to rod 56. In order to retard deflection of that portion of rod 56 which is disposed in passage 52, a trunnion bearing for transmitting axial loads from vane trunnion 36' to support cylinder 54 and a rod bearing for transmitting axial loads from rod 56 to vane trunnion 36 are disposed at a predetermined radial location near casing 31, radially inward of arcuate slot 70. v

The trunnion bearing comprises a portion 74 of support cylinder 54 having a predetermined inside diameter and a portion 76 of vane trunnion 36' having a predetermined outside diameter. At this same radial location, a portion 78 of passage 52 is formed with predetermined inside diameter and rod 56 has lands 80 formed thereon having a predetermined outside diameter. Portion 78 and lands 80 comprise the rod bearing. With the provision of the rod and trunnion bearings, the axial bearing loads are transferred from main shaft bearing 26 to support cylinder 54 (and thus to casing 31) as shown in FIG. 4. Also shown in FIG. 4 as a dotted arrow is the axial load reaction when rod and trunnion bearings are not used. Those skilled in the art will readily recognize that greater deflection of rod 56 will take place without the provision of rod and trunnion bearings since the bending moment acts over the entire length of the rod, with no restriction on the deflection of the rod. Those skilled in the art will readily perceive that the rod and trunnion bearings may be omitted, or that rod 56 and passage 52 be other than circular in crosssection, the only requirement necessary to render the present invention operable being that vane 32' be freely rotatable under those operating conditions in which the capability of vane pitch variation is desired. It is further recognized that rod 56 may be made solid without departing from the spirit of the invention, rods 56 being shown hollow so that lubricant may be conveniently introduced to main shaft bearing 26 by attaching an oil line 82 to the outer end of rod 56.

Referring now to FIG. 5, there is shown a second embodiment of the invention in which the interface between the rod and the boss on the front main frame is altered. Boss 58 on front main frame 49' includes a spool 82 having a predetermined inside diameter and a radially inward surface 84. Inner end of rod 56 forms an interference fit with the predetermined inside diameter of spool 82. The inner end of rod 56' includes an integral enlarged member 86 which cooperates with radially inward surface 84 to restrain spool 82 from radially inward movement. The inner end of rod 56 communicates with lubricant passage 63', as through aperture 88 in spool 82.

Referring now to FIG. 6, there is shown a third embodiment of the invention in which the interface of the rod with both the support cylinder and the boss on the front main frame is altered. Rod 56" has an intergral enlarged portion 90 at its outer end. Support cylinder 54', rather than having washer 66 thereon as in the first embodiment described above, has an aperture 92 and an outer surface 94. Enlarged portion 90 of rod 56" cooperates with outer surface 94 to restrain rod 56" from radially inward movement and aperture 92 cooperates with rod 56" to prevent movement of rod 56" in a direction normal to its axis. Boss 58 includes a spool 82 as described above in connection with the second embodiment. A nut 96 is threaded onto the inner end of rod 56" to secure 'spool 82 from radially inward movement.

The present invention has been described in connection with several arrangements for securing rod 56 to outer casing 31 and main frame 49. It will be clear to those skilled in the art, however, that rod 56 need only be restrained from radially inward movement and movement normal to the axis of rod 56 with respect to outer casing 31 and that each boss 58 on main frame 49 need only be restrained from radially inward and axial movement by corresponding rod 56 in order to be within the scope of the present invention. Further, those skilled in the art may perceive structure other than support cylinders 54 for supporting rods 56; however, the present invention contemplates any connection between rods 56 and outer casing 31 which will support rods 56 as described while permitting free rotation of vanes 32' as being within its scope. Also, while being described in connection with radially directed vanes 32', it is clear that to provide variable pitch blades having axes which are angled in a tangential direction is within the scope of the present invention.

Although several specific embodiments of the invention have been shown, those skilled in the art will perceive modifications other than those specifically pointed out which can be made without departing from the invention, and it is intended by the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.

What is claimed as new and desired to be secured by 8 Letters Patent of the United States is:

1. A mounting arrangement for securing a main shaft bearing of axial flow turbomachinery of the type having at least one stage of variable pitch stationary blades, the mounting arrangement comprising:

a. an annular outer casing supporting said blades;

b. a main frame for supporting said main shaft bearing, said main frame including a plurality of bosses; and

c. a plurality of supports for securing said main frame to said outer casing wherein each said blade of a selected stage has a support associated therewith, each said support including:

i. a rod disposed in a passage in said associated blade, wherein said blade is freely rotatable independently of said rod,

ii. said outer casing wherein said outer casing includes a first retaining means for restraining said rod from movement in a radially inward direction and second retaining means for restraining said rod from movement in a direction normal to the axis of said rod, and

. iii. one of said bosses wherein said boss is restrained from radially inward and axial movement by said rod.

2. The mounting arrangement recited in claim 1- wherein each said support further includes:

- a. a hollow support cylinder mounted to said casing, said support cylinder including an outer end, said outer end including said first and second retaining means, and an arcuate slot radially inward of said outer end;

b. a blade trunnion coaxially mounted to each said associated blade, wherein said blade trunnion is disposed within said support cylinder and said passage extends through said blade trunnion; and

c. rotation means for rotating said blade trunnion about its axis, wherein said rotation means extends through said arcuate slot and is secured in torque transmitting relation to said blade trunnion.

3. The mounting arrangement recited in claim 2 wherein each support further comprises:

a. a trunnion bearing 'for transmitting forces normal to the axis of said blade trunnion to said support cylinder, wherein said trunnion bearing is located at a predetermined radial location; and

b. a rod bearing for transmitting forces normal to the axis of said rod to said blade trunnion, wherein said rod bearing is located at said predetermined radial location.

4. The mounting arrangement recited in claim 3 wherein:

a. said predetermined radial location is radially inward of said arcuate slot;

b. said trunnion bearing comprises:

i. a portion of said support cylinder at said predetermined radial location having a predetermined inside diameter, and

ii. a portion of said blade trunnion at said predetermined radial location having an outside diameter substantially equal to but no greater than said predetermined inside diameter of said support cylinder; and

c. said rod bearing comprises:

i. a portion of said passage at said predetermined radial location having a predetermined inside diameter, and

ii. said rod includes lands located at said predetermined radial location, said lands having a predetermined outside diameter substantially equal to but no greater than said predetermined inside diameter of said passage.

5. The mounting arrangement recited in claim 2 wherein:

a. said rotation means comprises an eccentric crank wherein said eccentric crank cooperates with said support cylinder and said blade trunnion to restrain said associated blade from radially inward movement; and

b. said associated blade includes a circular shoulder coaxial with said associated blade, wherein said shoulder cooperates with said outer casing to restrain said associated blade from radially outward movement.

6. The mounting arrangement recited in claim 2 wherein:

a. said main frame includes a plurality of lubricant passages communicating with said main shaft bearmg;

b. said rod is hollow and said inner end of said rod communicates with one of said lubricant passages.

7. The mounting arrangement recited in claim 2 wherein:

a. said rod has a generally radially directed axis; and

b. said support cylinder is generally radially directed.

8. The mounting arrangement recited in claim 2 wherein:

' a. said outer end of said support cylinder includes a washer having an aperture therein; b. said rod includes an outer end and an inner end;

c. said outer end of said rod extends through said aperture and has a nut threaded thereon;

d. said first retaining means comprises said washer in cooperation with said nut, wherein said rod is pretensioned by said nut cooperating with said washer;

e. said second retaining means comprises said aperture in said washer in cooperation with said outer end of said rod; and

f. said boss includes a spool for receiving said inner end of said rod wherein said rod extends into said spool and is fixed thereto.

9. The mounting arrangement recited in claim 2 wherein:

a. said outer end of said support cylinder includes a washer having an aperture therein;

b. said rod is pretensioned and includes an inner end and an outer end;

0. said outer end of said rod extends through said aperture and has a nut threaded thereon;

(1. said first retaining means comprises said washer in cooperation with said nut;

e. said second retaining means comprises said aperture in said washer in cooperation with said outer end of said rod;

f.- said boss includes a spool wherein said spool has a predetermined inside diameter and a radially inward surface;

g. said inner end of said rod is disposed in said spool and has an outside diameter fonning an interference fit with said predetermined inside diameter of said spool; and

h. said inner end'of said rod includes an enlarged member integral therewith, wherein said enlarged member cooperates with said radially inward surface of said spool to restrain said spool from radially inward movement.

10. The mounting arrangement recited in claim 2 wherein:

a. said outer end of said support cylinder includes an aperture and an outer surface;

b. said rod is pretensioned and includes an inner end and an outer end;

c. said outer end of said rod extends through said aperture in said outer end and has an enlarged portion integral therewith;

d. said first retaining means comprises said enlarged portion in cooperation with said outer surface;

e. said second retaining means comprises said outer end of said rod in cooperation with said aperture in said outer end;

f. said boss includes a spool having a predetermined inside diameter and a radially inward surface; and

g. said inner end of said rod extends through said spool and has a predetermined outside diameter forming an interference fit with said predetermined inside diameter of said spool, said inner end of said rod further has a nut threaded thereon, wherein said nut cooperates with said radially inward surface to restrain said spool from radially inward movement.

11. The mounting arrangement recited in claim 1 wherein said main frame is a truncated cone including an inner end having said main shaft bearing secured thereto and an outer periphery having said bosses secured thereto. 

1. A mounting arrangement for securing a main shaft bearing of axial flow turbomachinery of the type having at least one stage of variable pitch stationary blades, the mounting arrangement comprising: a. an annular outer casing supporting said blades; b. a main frame for supporting said main shaft bearing, said main frame including a plurality of bosses; and c. a plurality of supports for securing said main frame to said outer casing wherein each said blade of a selected stage has a support associated therewith, each said support including: i. a rod disposed in a passage in said associated blade, wherein said blade is freely rotatable independently of said rod, ii. said outer casing wherein said outer casing includes a first retaining means for restraining said rod from movement in a radially inward direction and second retaining means for restraining said rod from movement in a direction normal to the axis of said rod, and iii. one of said bosses wherein said boss is restrained from radially inward and axial movement by said rod.
 2. The mounting arrangement recited in claim 1 wherein each said support further includes: a. a hollow support cylinder mounted to said casing, said support cylinDer including an outer end, said outer end including said first and second retaining means, and an arcuate slot radially inward of said outer end; b. a blade trunnion coaxially mounted to each said associated blade, wherein said blade trunnion is disposed within said support cylinder and said passage extends through said blade trunnion; and c. rotation means for rotating said blade trunnion about its axis, wherein said rotation means extends through said arcuate slot and is secured in torque transmitting relation to said blade trunnion.
 3. The mounting arrangement recited in claim 2 wherein each support further comprises: a. a trunnion bearing for transmitting forces normal to the axis of said blade trunnion to said support cylinder, wherein said trunnion bearing is located at a predetermined radial location; and b. a rod bearing for transmitting forces normal to the axis of said rod to said blade trunnion, wherein said rod bearing is located at said predetermined radial location.
 4. The mounting arrangement recited in claim 3 wherein: a. said predetermined radial location is radially inward of said arcuate slot; b. said trunnion bearing comprises: i. a portion of said support cylinder at said predetermined radial location having a predetermined inside diameter, and ii. a portion of said blade trunnion at said predetermined radial location having an outside diameter substantially equal to but no greater than said predetermined inside diameter of said support cylinder; and c. said rod bearing comprises: i. a portion of said passage at said predetermined radial location having a predetermined inside diameter, and ii. said rod includes lands located at said predetermined radial location, said lands having a predetermined outside diameter substantially equal to but no greater than said predetermined inside diameter of said passage.
 5. The mounting arrangement recited in claim 2 wherein: a. said rotation means comprises an eccentric crank wherein said eccentric crank cooperates with said support cylinder and said blade trunnion to restrain said associated blade from radially inward movement; and b. said associated blade includes a circular shoulder coaxial with said associated blade, wherein said shoulder cooperates with said outer casing to restrain said associated blade from radially outward movement.
 6. The mounting arrangement recited in claim 2 wherein: a. said main frame includes a plurality of lubricant passages communicating with said main shaft bearing; b. said rod is hollow and said inner end of said rod communicates with one of said lubricant passages.
 7. The mounting arrangement recited in claim 2 wherein: a. said rod has a generally radially directed axis; and b. said support cylinder is generally radially directed.
 8. The mounting arrangement recited in claim 2 wherein: a. said outer end of said support cylinder includes a washer having an aperture therein; b. said rod includes an outer end and an inner end; c. said outer end of said rod extends through said aperture and has a nut threaded thereon; d. said first retaining means comprises said washer in cooperation with said nut, wherein said rod is pretensioned by said nut cooperating with said washer; e. said second retaining means comprises said aperture in said washer in cooperation with said outer end of said rod; and f. said boss includes a spool for receiving said inner end of said rod wherein said rod extends into said spool and is fixed thereto.
 9. The mounting arrangement recited in claim 2 wherein: a. said outer end of said support cylinder includes a washer having an aperture therein; b. said rod is pretensioned and includes an inner end and an outer end; c. said outer end of said rod extends through said aperture and has a nut threaded thereon; d. said first retaining means comprises said washer in cooperation with said nut; e. said second retainIng means comprises said aperture in said washer in cooperation with said outer end of said rod; f. said boss includes a spool wherein said spool has a predetermined inside diameter and a radially inward surface; g. said inner end of said rod is disposed in said spool and has an outside diameter forming an interference fit with said predetermined inside diameter of said spool; and h. said inner end of said rod includes an enlarged member integral therewith, wherein said enlarged member cooperates with said radially inward surface of said spool to restrain said spool from radially inward movement.
 10. The mounting arrangement recited in claim 2 wherein: a. said outer end of said support cylinder includes an aperture and an outer surface; b. said rod is pretensioned and includes an inner end and an outer end; c. said outer end of said rod extends through said aperture in said outer end and has an enlarged portion integral therewith; d. said first retaining means comprises said enlarged portion in cooperation with said outer surface; e. said second retaining means comprises said outer end of said rod in cooperation with said aperture in said outer end; f. said boss includes a spool having a predetermined inside diameter and a radially inward surface; and g. said inner end of said rod extends through said spool and has a predetermined outside diameter forming an interference fit with said predetermined inside diameter of said spool, said inner end of said rod further has a nut threaded thereon, wherein said nut cooperates with said radially inward surface to restrain said spool from radially inward movement.
 11. The mounting arrangement recited in claim 1 wherein said main frame is a truncated cone including an inner end having said main shaft bearing secured thereto and an outer periphery having said bosses secured thereto. 